Arab J Geosci DOI 10.1007/s12517-014-1628-z
ORIGINAL PAPER
Temporal and spatial variations of the water erosion rate Jamal Mosaffaie & Mohammad Reza Ekhtesasi & Mohammad Taghi Dastorani & Hamid Reza Azimzadeh & Mohammad Ali Zare Chahuki
Received: 18 June 2014 / Accepted: 4 September 2014 # Saudi Society for Geosciences 2014
Abstract Understanding the erosion dynamics and recognizing sensitive times and places to erosion within the catchment are necessary for erosion control. The seasonal and spatial variability of soil erosion under different contrasting lithologic conditions was studied in Vartavan catchment of Qazvin province of Iran. For this purpose, sediment trappers and erosion pins were placed in each parent material unit and were monitored at the end of each season. The results showed that the erosion rate of Vartavan catchment has large variations spatially and temporally. Based on the average weight of sediments in trappers, soil erosion rate is reduced correspondingly in units of light tuff (178.2g), black shale (34.4 g), red mudstone (29.9 g), andesite (21.7 g), dark tuff (16.7 g), sandstone (14.9 g), red sandstone (9.8 g), shale limestone (9.5 g), and eventually orbitolina limestone (6.5 g). The seasonal variation of erosion revealed that autumn has the maximum rate of erosion (71 %) which then decreases during the spring (19 %) and winter (10 %) until it reaches the minimum rate in summer. Understanding seasonal variations and identifying J. Mosaffaie (*) : M. R. Ekhtesasi : H. R. Azimzadeh Faculty of Natural Resources, Yazd University, Yazd, Iran e-mail:
[email protected] J. Mosaffaie e-mail:
[email protected] M. R. Ekhtesasi e-mail:
[email protected] H. R. Azimzadeh e-mail:
[email protected] M. T. Dastorani Faculty of Natural Resources and Environment, Ferdowsi University of Mashhad, Mashhad, Iran e-mail:
[email protected] M. A. Zare Chahuki Faculty of Natural Resources, University of Tehran, Karaj, Iran e-mail:
[email protected]
the critical months when the most amount of erosion occurs are essential for outlining soil conservation plans in specific lithological units. Keywords Sediment trapper . Erosion pin . Erosion dynamic . Vartavan catchment
Introduction Watershed degradation as a result of soil erosion and sedimentation is considered to be one of the major environmental problems in Iran (Bagherzadeh and Mansouri Daneshvar 2013). This phenomenon is a highly dynamic and complex process which has negative onsite and offsite effects (Prasannakumar et al. 2012). It reduces not only the storage capacity of the downstream reservoirs but also deteriorates the productivity of the watershed (Arekhi et al. 2012a, b). After construction of Sefid-Rud dam, the measured sedimentation rate was about 45 million m3/year causing storage loss of over 30 % in 18 years. Hence, erosion control at catchments such as Vartavan located in the upstream side of this dam is essential. This highlights the need for data allowing delineation of critical periods and sediment source areas that need to be prioritized for soil conservation. Identification of such periods and hotspots will help in applying a targeted response directing resources to areas of high risk rather than spreading them equally across the landscape. This requires a basic understanding of the temporal and spatial variations of soil erosion and sediment transport at the scale of a river catchment (Haregeweyn et al. 2013). The parent material plays a key role in determining the geomorphologic processes affecting weathering rates, soil development, and slope forms (Cerdà 2002). Other factors such as rainfall characteristics, topography features, soil texture, permeability, organic matter content, antecedent soil moisture, and soil management also affect runoff and soil
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erosion (Kavian et al. 2014). Most of these factors have seasonal and spatial changes. Climatic conditions, especially under seasonally contrasting climates, affect soil moisture, organic matter, and biotic activity. Hence, seasonal and spatial changes of soil erosion should be considered as a dynamic characteristic of soils. Mediterranean environments are subject to highly dynamic and complex soil erosion due to climate characterized by contrasting seasons (Cerdà et al. 2010). These dynamic characteristics of soil erosion have been focused by many studies. For instance, seasonal behavior of infiltration and runoff processes has been measured in semiarid and temperate regions (Jorgensen and Gardner 1987; Blackburn et al. 1990). It has been widely accepted that the infiltration capacity of soils is higher under dry conditions due to the high matric suction and the action of capillarity forces (Cerdà 1999a; Beven 2012). Runoff is always greater during the wet season than during the dry season, although hydrophobic layers can induce larger runoff rates during drought and dry periods (Cerdà 1996, 1997). Cerdà (2002) studied the effect of season and parent material on water erosion using the data collected via simulated rainfall and showed that autumn and marl have greater runoff and erosion rates. Khanchoul et al. (2009) found out the reasons for the differences in suspended sediment yield between seasons by analyzing the relative effects of factors such as lithology, topography, and land use. Cerdà (1998) studied the seasonal and spatial variability of soil erosion under contrasting slope aspects using rainfall simulation experiments and concluded that seasonally, runoff sediment concentration was highest in autumn, decreasing in winter and spring, and increased slightly in summer when runoff and erosion rates were very low. Ferreira and Panagopoulos (2014) updated RUSLE using seasonal rainfall erosivity data and vegetation cover series data and concluded that autumn contributes more to annual erosion with 56 %, followed by spring with 20 %, summer with 12 %, and winter with 11 %. These studies have been done because knowledge about critical periods and zones is essential for erosion control and delineating appropriate strategies. It is of great importance to create a decision support system, allowing the delineation of seasonal strategies for different sediment source scenarios. However, in addition to limited researches, most of them have been done using models or rain simulator that their results may be different from what actually occurs in nature. This study investigates the seasonal and spatial variations of soil erosion in a Mediterranean environment (Vartavan catchment) using direct measurements of erosion. Using the results of this research, erosion rate can be reduced by applying management techniques spatially (focus conservative practices in sensitive places) or temporally (preservation of vegetation and to prevent plowing at critical seasons).
Materials and methods Description of the study area The study area refers to the Vartavan catchment located in Qazvin province of Iran, with the geographic coordinates from 36° 24′ N to 36° 29′ N and 50° 07′ E to 50° 12′ E (Fig. 1). The total area of catchment is 4,811 ha, with the minimum elevation of 1,300 and maximum of 2,640 m above the sea level. The terrain type of catchment is predominantly mountainous with average slope of 40 %. The general direction of the slope is northeast. Arable lands are plowed and cultivated twice a year (in autumn and spring). Using precipitation data from 1992 to 2012, the mean annual precipitation is 372 mm. The precipitation concentration is located in winter (36 %), followed by spring (32 %) and autumn (30 %), and drought coincides with the summer (2 %). The average annual temperature is 10.2 °C (Falar-Kaman station in the vicinity of catchment). July with an average temperature of 25.4 °C is the warmest month, and January is the coldest month with an average temperature of 0.4 °C. The climate is Mediterranean and characterized by four seasons. The region is semiarid but cold and snowy in winters and temperate in summers. Over the entire year, the most common forms of precipitation are thunderstorms (most likely around May), moderate rain, and moderate snow (most likely around January). Figure 1 shows the location of the study area in Iran. Mapping lithological units Initially, a digital geological map of the catchment with scale of 1/100,000 was prepared and general understanding was obtained from the formations and rock units in the region. In the next step, using different remote sensing techniques such as Google earth images and ETM+ imagery analysis and making various false color composites (FCC) and extensive field visits, the boundary of lithological units was refined. Seasonal monitoring of the relative erosion of lithological units A range of techniques is available for measuring or inferring erosion and sediment mobilization (Collins and Walling 2004). In natural conditions, sediment yield can be measured by dynamic (e.g., collector devices, Gerlach troughs) and volumetric recordings (erosion pins, profilometers) (De Ploey and Gabriels 1980). Sediment yield values depend on the technique used, and erosion values recorded by volumetric techniques have been claimed to be higher than the dynamic ones (Takei et al. 1981; Sala 1988). Seasonal changes in soil bulk density, due to variations in soil moisture and swelling, can introduce an additional source of error in erosion measurements (Sirvent et al. 1997). In this study, sediment trappers and erosion pins were used to determine the relative erosion of different units.
Arab J Geosci Fig. 1 Location map of the Vartavan catchment in Qazvin province of Iran
Sediment trappers For sediment trapping, three trappers were installed in each lithological unit perpendicular to the slope of 22° (catchment mode slope) so that the slope length of the upstream side was at least 22 m. Trappers were glass wares with a height of 15 cm and 6 cm in diameter. The metal door of these glass jars was cut in dimensions of 0.5 × 5 cm (Fig. 2). A cubic grid mesh (10 × 10 cm with 1 cm height and grid dimensions of 0.8 × 0.8 cm) made of galvanized was placed over each trapper and finally, a piece of stone was placed on a cubic mesh to hide the mesh and trappers from the sight of people and livestock attention. The amount of sediments collected in trappers was collected at the end of each season and, after drying in the open air, was weighed with accuracy of 0.1 g for a period of 2 year. ANOVA was used to assess any statistically significant differences between sediments collected in trappers.
beaten on the ground to the height of 10 cm (Fig. 2). The lengths of the pins left exposed above the soil surface were recorded at the end of each season by setting a metal washer on the ground and taking measurements with a depth gauge.
Results Map of lithological units and trapping points The digital geological map at scale of 1:100,000 showed that the area is covered mainly by sedimentary and igneous rocks. Nine photo-lithological units have been detected using Landsat ETM+ images processing including andesite, orbitolina limestone, black shale, red mudstone, light tuff, dark tuff, sandstone, shale limestone, and red sandstone. The map of lithological units and trapping points has been shown in Fig. 3.
Erosion pins The insertion of nails into the surface of the slopes can provide a datum which erosion or deposition can be manually assessed on the basis of the length of pin exposed or movement of a washer placed on the pin. Eighty-one pins constructed of steel and covered by a coat of zinc were also used for erosion measurement. The length of pins was 15 cm and 4 or 6 mm in diameter, depending on the rock hardness. In the vicinity of each trapper, three pins in triangular arrangement and at 1.5 m distance were
Fig. 2 Two samples of sediment trapper (a) and erosion pin (b)
Arab J Geosci Fig. 3 The map of trapper locations and lithological units
Sediment trappers The dry weight of sediments collected in 27 trappers (3 trappers in each lithological unit) has been presented separately for each season in Table 1. The diagram of the average weight of sediment collected in trappers over 2 years monitoring has been presented for each lithological unit in Fig. 4. Based on these data, soil erosion rate is reduced correspondingly in units of light tuff (178.2 g), black shale (34.4 g), red mudstone (29.9 g), andesite (21.7 g), dark tuff (16.7 g), sandstone (14.9 g), red sandstone (9.8 g), shale limestone (9.5 g), and eventually orbitolina limestone (6.5 g). The sediment values were very high in light tuff, black shale, and red mudstone especially during autumn and spring. Lower values were accumulated in andesite, dark tuff, and sandstone trappers although were still greater than for shale and orbitolina limestone. These data were also interpreted seasonally based on Jalali calendar, considering autumn (23 September to 21 December), winter (22 December to 20 March), spring (21 March to 21 June), and summer (22 June to 22 September). The average weight of sediment collected in trappers for each season was calculated, and the diagram of the relative contribution of each season to annual soil erosion has been presented in Fig. 5. In summer, most of the trappers did not
accumulate any sediment, which demonstrates that there is no runoff causing soil erosion. Autumn has the maximum rate of erosion (71 %), and then erosion decreases accordingly during the spring (19 %) and winter (10 %) until it reaches the minimum rate in summer. Erosion pins The length measurements of 81 pins (9 pins in each lithological unit) have been presented in Table 2. The graph of seasonal and spatial (for each lithological unit) variations of the pins’ record data over 2 years monitoring has been presented in Fig. 6. Many of the units have negative recordings in winter. Most fluctuations of the pin measurements are related to those of the lithic tuff unit.
Discussion Based on the average weight of sediments in trappers, soil erosion rate is reduced accordingly in units of light tuff, black shale and red mudstone, andesite, dark tuff, sandstone, shale limestone, and eventually orbitolina limestone. The relationship between erosion and parent material was also confirmed
Arab J Geosci Table 1 The weight of sediment accumulated in the trappers Trapper
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
Unit
Andesite
Light tuff
Shale limestone
Dark tuff
Black shale
Red mudstone
Sandstone
Red sandstone
Orbitolina limestone
Average
Sediment weight (g)—2012
Sediment weight (g)—2013
Autumn
Winter
Spring
Summer
Autumn
Winter
Spring
Summer
11.3 14.8 10.7 71.4 375.4 21.2 7.3 2.9 5.6 13.1 13.4 7.4 19.2 18.7
Snow 5.3 3.9 8.2 5.5 8.1 2 0 3.1 1.8 2.9 Snow 8.3 3.2
7.8 4.7 6.7 19.1 14.3 11.4 2.3 – 5.4 – 5.2 6.4 13.6 12.6
0 0 0 0 0 0 – 0 0 0 0 0 0 0
Snow 9.8 Snow 20.3 18.7 22.7 3.9 5.4 6.8 10.9 8 Snow 17.3 –
Snow 4.9 4.3 6.9 8.3 7.6 1.4 1.7 2.8 3.1 2.4 Snow 7.1 6.2
3.9 8.2 5.1 16.3 17.1 12.4 3.9 – 4.8 7.1 4.9 5.8 10.7 13.1
0 – 0 0 0 0 0 0 – 0 0 0 0 0
15.3 15.1 15.7 13.9 5.7 5.9 10.3 6.1 5.5 7.1 0.9 4.2 5.4 26.1
4.4 5.8 8 3.4 1.2 4.6 3.8 1.2 1.9 1.1 1.1 0 1.2 3.6
7.8 10.1 9.4 8.3 5.7 4.5 3.1 2.4 – 4.2 3.5 0.4 2.9 7.2
– 0 0 0 0 0 0 0 0 0 0 0 0 0.0
16.2 Snow 13.7 14.2 7.9 8.1 6.9 4.8 6.5 6.8 1.4 Snow 4.9 10.2
5.8 6.1 6.2 7.2 2.4 3.6 3.9 3.3 2.7 2.5 1.4 Snow 1.3 4.3
11.6 – 9.7 10.4 6.1 3.5 2.8 3.7 – 4.3 2.7 1.2 2.6 7.2
– 0 0 0 0 0 0 0 0 0 0 0 0 0.0
by other studies (Cerdà 1999b, 2002). Because of the loose nature of minerals such as plagioclase feldspars, light tuff unit has low resistance against erosion. The block breakage of
limestone and large pieces of stones which form a protective coating against erosion is the major reason for the low erosion of limestone units (shale limestone and orbitolina limestone).
Fig. 4 Spatial variability of soil erosion
Fig. 5 Contribution of each season to annual soil erosion
Arab J Geosci Table 2 The height of pins in different lithological units Unit
Andesite
Light tuff
Shale limestone
Dark tuff
Black shale
Red mudstone
Pin
Pin height (mm) 2012
Pin height (mm) 2013
Autumn
Winter
Spring
Summer
Autumn
Winter
Spring
Summer
1 2 3 4 5 6 7 8 9 10 11 12 13 14
6 5 1 2 7 3 0 −1 3 12 23 21 29 17
S S S 0 0 3 0 1 0 −9 −6 −10 −7 −6
2 5 3 0 2 4 −1 0 1 7 −2 −1 2 −1
0 0 0 0 0 0 0 0 0 0 0 0 0 0
4 2 3 2 6 5 1 2 2 9 6 7 8 13
S S S 2 0 3 0 1 2 −6 −11 −8 −5 −10
3 2 4 1 4 1 0 −1 1 3 −2 −1 1 −1
0 0 0 A 0 0 0 0 0 0 0 0 0 0
15 16 17 18 19 20 21 22 23 24 25
36 14 15 10 3 1 2 0 1 0 2
−1 −2 0 −7 −3 −6 −1 0 2 2 −1
4 3 2 0 1 2 1 −1 A A −1
0 0 0 0 A 0 0 0 0 0 0
5 10 6 11 2 3 2 1 2 0 −1
−3 −2 −1 −2 −3 −2 −2 2 −1 1
3 2 1 2 1 2 0 −1 A −1
0 0 0 0 A 0 0 0 0 0
26 27 28 29 30 31 32
−1 −3 2 3 2 2 4
−2 −4 0 −3 −2 −1 −3
0 −2 A A A 3 1
0 0 0 0 0 0 0
2 3 5 2 3 1 4
−1 −3 −2 −1 −3 0 −2 −3
0 −1 −1 2 3 1 2 3
A 0 0 0 0 0 0 0
33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
3 1 2 4 3 5 4 8 6 5 3 9 3 6 3
−5 S S S 5 4 0 0 0 −2 1 2 3 5 9
2 −1 1 2 1 3 2 1 7 4 2 1 5 1 3
0 0 0 0 0 0 0 0 0 0 A A 0 0 0
2 3 3 5 6 3 3 7 4 5 4 3 7 8 5
−3 S S S 4 1 2 0 2 3 2 0 3 4 6
2 1 −1 0 2 2 3 1 5 6 3 2 4 A 5
0 0 0 0 0 0 0 0 0 0 A A 0 0 0
Arab J Geosci Table 2 (continued) Unit
Sandstone
Red sandstone
Orbitolina limestone
Pin
Pin height (mm) 2012
Pin height (mm) 2013
Autumn
Winter
Spring
Summer
Autumn
Winter
Spring
Summer
48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
7 4 7 3 5 0 2 4 2 5 3 0 1 0 1 2 1 3
4 −7 −9 −6 −5 0 0 3 5 1 1 0 4 0 0 −3 0 2
4 3 A 2 3 −1 −2 5 3 1 0 1 2 1 2 1 2 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
5 3 6 4 2 4 1 2 6 3 2 2 0 0 1 3 2 4
8 −2 3 −4 −2 −3 −2 3 2 1 2 0 1 2 3 1 0 0
A 3 2 −1 2 −1 0 3 5 2 1 2 0 1 1 0 4 2
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81
2 5 2 0 2 1 3 1 1 0 1 0 0 −1 0 1
1 2 0 1 −1 0 −1 0 0 1 1 1 0 −1 0 −1
0 2 3 1 2 1 2 1 0 1 1 0 0 0 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
2 3 0 5 2 3 2 1 0 1 0 1 0 1 0 1
2 1 A A −2 −1 −1 0 1 −1 S S S 1 0 −2
1 0 1 3 1 2 1 0 1 0 1 0 0 1 0 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
S covered pins with snow (lost data), A absence pins (lost data)
On the other hand, seams in the limestone units maintain water in secondary porosity which leads to suitable moisture condition for the vegetation establishment. Relatively low erosion of the sandstone units can be also due to the remarkable mean diameter of soil particles and weight resistance of particles against the shear force of runoff. Other studies have also resulted in low relative erosion rate for sandstone units (Cerdà 1999b, 2002). Fine particle units such as black shale and red mudstone have little resistance to the shear force of runoff, resulting in high rates of erosion in these units.
Andesite and dark tuff units with medium-diameter particles and suitable ecological conditions for vegetation establishment have moderate rate of erosion. Figure 4 shows that light tuff unit, especially in the first year, has much greater erosion than the other units. The reason for this drastic difference is the sediments accumulated in the trappers 4 and 5 in autumn which causes an anomaly in Fig. 4. This anomaly is caused by severe rill erosion resulting from autumn extreme rainstorm on the slopes of this unit, especially where the trappers have been installed. Meanwhile, trappers of
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Fig. 6 Seasonal and spatial variations of pins’ record data
other units have only collected sediments of surface erosion. When visiting the region, the signs of rill erosion were evident on the soil surface of light tuff unit. The average weight of sediments accumulated in trappers of black shale and red mudstone units is also nearly high, and therefore the erosion of these units is also high. The high erosion of light tuff unit may be approved by erosion pin method (Table 2 and Fig. 6). Negative pin readings, however, can pose an important problem for the monitoring of erosion rates and reflect a number of factors including deposition and expansion of soil surface resulting from temperature or moisture fluctuations. Seasonal changes in soil bulk density, due to variations in soil moisture and swelling, can introduce an additional source of error. For instance, the mean of the negative signs at the end of winter is higher than other seasons especially in the light tuff, dark tuff, shale limestone, and red mudstone units. This is probably due to differences in the clay content of these units and therefore differences in the rate of swelling and shrinkage of their soils, so at the end of the winter, these soils take an osteoporotic state and will cause the negative signs on the pins. Thus, for measuring the erosion, trappers are more efficient than erosion pins. The reason is that negative or positive recording of pins, in addition to erosion rate, depends on other factors which are unavoidable. These factors include the rate of swelling and shrinkage of soils, redistribution of eroded soil particles, and positioning the pins in the sites of erosion, transport, or deposition. Sirvent has also declared that seasonal changes in soil bulk density, due to variations in soil moisture and swelling, can introduce a source of error in erosion measurements using pins (Sirvent et al. 1997). The seasonal variation of erosion was confirmed by both methods (sediment trappers and erosion pins), and the study showed a greater erosion rate during autumn, when runoff is very high and large amounts of loose sediments rest on the soil surface after the very dry and hot summer. In autumn, there is a lag between rainfall events and vegetation growth and therefore the surface of soil is exposed to the first intensive rainfall episodes after a long dry summer. Cerdà has also
concluded that autumn (between September and December) is the season with the highest soil erodibility due to the lack of vegetation and litter cover and the intense tillage (Cerdà and Doerr 2007). This part of the result is consistent with previous researches conducted by Cerda and Ferreira (Cerdà 1998, 2002; Ferreira and Panagopoulos 2014). But the order of relative contribution of other seasons to sediment yield is somewhat different from previous researches. Our data indicates that erosion rate decreases during the spring and winter until it reaches the minimum rate in summer (Figs. 5 and 6). In spring, the vegetation cover is denser than autumn which protects the soil. Despite the fact that winter has the most volume of annual precipitation, erosion in winter is less than in autumn and spring. This can be explained by the fact that the major precipitation in winter is snow with slow hydrological response. In summer, there was no sediment in trappers because there was no precipitation and no runoff thereafter. However, in other regions with different temperature, climate, and precipitation patterns, different results may be achieved. Our results highlight the significance of maintaining the soil cover throughout the year, especially in the higher precipitation periods, in order to avoid high soil erosion rate. An optimal balance between rainfall and vegetation cover is essential to reduce soil erosion during the year.
Conclusion The seasonal and spatial variability of soil erosion was studied in Vartavan catchment of Qazvin province of Iran. The study confirmed the seasonal and spatial variations in soil erosion rates. Our results showed that this dynamic phenomenon is intensely affected by changes in lithological units, rainfall erosivity, and vegetation cover throughout the year. It should be emphasized that the areas with highly susceptible soil conditions would need special priority for the implementation of soil conservation practices. For effective watershed planning, there must be coordination between vegetative and structural control measures. It is important to maintain the soil cover throughout the year, especially in the higher precipitation periods, in order to avoid high soil erosion rate. Understanding seasonal variations and identifying the critical months when most erosion occurs are essential for outlining suitable soil conservation plans in specific lithological units.
References Arekhi S, Niazi Y, Kalteh AM (2012a) Soil erosion and sediment yield modeling using RS and GIS techniques: a case study, Iran. Arab J Geosci 5:285–296
Arab J Geosci Arekhi S, Shabani A, Rostamizad G (2012b) Application of the modified universal soil loss equation (MUSLE) in prediction of sediment yield (case study: Kengir Watershed, Iran). Arab J Geosci 5:1259– 1267 Bagherzadeh A, Mansouri Daneshvar M (2013) Evaluation of sediment yield and soil loss by the MPSIAC model using GIS at Golestan watershed, northeast of Iran. Arab J Geosci 6(9):3349–3362 Beven K (2012) Rainfall-runoff modelling: the primer, 2nd edn. Lancaster University, UK Blackburn WH, Pierson FB, Seyfried MS (1990) Spatial and temporal influence of soil frost on infiltration and erosion of sagebrush rangelands. Water Res Bull 26:991–997 Cerdà A (1996) Seasonal variability of infiltration rates under contrasting slope conditions in Southeast Spain. Geoderma 69:217–232 Cerdà A (1997) Seasonal changes of the infiltration rates in a typical Mediterranean scrubland on limestone in southeast Spain. J Hydrol 198(1–4):198–209 Cerdà A (1998) The influence of aspect and vegetation on seasonal changes in erosion under rainfall simulation on a clay soil in Spain. Can J Soil Sci 78:321–330 Cerdà A (1999a) Seasonal and spatial variations in infiltration rates in badland surfaces under Mediterranean climatic 534 conditions. Water Resour Res 35:319–328 Cerdà A (1999b) Parent material and vegetation affect soil erosion in eastern Spain. Soil Sci Soc Am J 63:362–368 Cerdà A (2002) The effect of season and parent material on water erosion on highly eroded soils in eastern Spain. J Arid Environ 52:319–337 Cerdà A, Doerr SH (2007) Soil wettability, runoff and erodibility of major dry-Mediterranean land use types on calcareous soils. Hydrol Process 21:2325–2336 Cerdà A, Hooke J, Romero-Diaz A, Montanarella L, Lavee H (2010) Soil erosion on Mediterranean type-ecosystems. Land Degrad Dev 21: 71–74, Editors Collins AL, Walling DE (2004) Documenting catchment suspended sediment sources: problems, approaches and prospects. Prog Phys Geogr 28:159–196
De Ploey J, Gabriels D (1980) Measuring soil loss and experimental studies. Willey. 63–108 Ferreira V, Panagopoulos T (2014) Seasonality of soil erosion under Mediterranean conditions at the Alqueva dam watershed. Environ Manag 54:67–83 Haregeweyn N, Poesen J, Verstraeten G, Govers G, De Vente J, Nyssen J, Deckers J, Moeyersons J (2013) Assessing the performance of a spatially distributed soil erosion and sediment delivery model (WATEM/SEDEM) in Northern Ethiopia. Land Degrad Dev 24: 188–204 Jorgensen DW, Gardner TW (1987) Infiltration capacity of disturbed soils: temporal change and lithologic control. Water Res Bull 23: 1161–1172 Kavian A, Azmoodeh A, Solaimani K (2014) Deforestation effects on soil properties, runoff and erosion in northern Iran. Arab J Geosci 7(5):1941–1950 Khanchoul K, Altschul R, Assassi F (2009) Estimating suspended sediment yield, sedimentation controls and impacts in the Mellah Catchment of Northern Algeria. Arab J Geosci 2: 257–271 Prasannakumar V, Vijith H, Abinod S, Geetha N (2012) Estimation of soil erosion risk within a small mountainous subwatershed in Kerala, India, using Revised Universal Soil Loss Equation (RUSLE) and geo-information technology. Geosci Front 3:209–215 Sala M (1988) Slope runoff and sediment production in two Mediterranean mountain environments. Catena Suppl 12:13– 29 Sirvent J, Desir G, Gutierrez M, Sancho C, Benito G (1997) Erosion rates in badland areas recorded by collectors, erosion pins and profilometer techniques (Ebro Basin, NE-Spain). Geomorphology 18:61–75 Takei A, Kobashi S, Fukushima Y (1981) Erosion and sediment transport measurement in a weathered granite mountain area. In: Symposium on erosion and sediment transport measurement, Florence. Int Assoc Hydrol Sci 133:493–502
